Alaska National Parks: Bering Land Bridge NP

Kobuk Valley National Park is encircled by the Baird and Waring mountain ranges. The park povides protection for several important geographic features, including the central portion of the Kobuk River, the 25-sqaure-mile Great Kobuk Sand Dunes, and the Little Kobuk and Hunt River dunes.
"With adjacent Noatak National Preserve and Kobuk Valley National Park, Gates of the Arctic comprises one of the world's largest parkland areas."
Sand created by the grinding action of ancient glaciers has been carried to the Kobuk Valley by both wind and water. Dunes now cover much of the southern portion of the Kobuk Valley, where they are naturally stabilized by vegetation. River bluffs, composed of sand and standing as high as 150 feet, hold permafrost ice wedges and the fossils of Ice Age mammals.